have you consulted a dermatologist? That would be my only advise since your condition is severe. If you are having itchy scalp, then when you scratch, you irritate your follicles causing your hair to fall out. It could be any of a number of causes, so I really do suggest seeing a dermatologist for advice and make a note to him/her that you would like to explore more "natural" solutions

Other than that, what products are you using? There could be something in your products to which you have a reaction causing your scalp to be itchy and flaky. For example, some shampoos are really harsh and will strip your hair and scalp of it's natural oil (sebum). They can also cause irritation of the scalp and cause it to be dry. If your hair is not well moisturized and you are scratching like crazy, your hair will fall out. If you are cowashing, you need to rinse your scalp REALLY well after, this will make sure you don't have any conditioner left on your scalp, which for some (like me) caused a really itchy scalp. Also look at your diet as well. Hemp oil and flax seed oil are both good sources of omega 3s and other essential fatty acids that help strengthen hair.

HTH (see a derm though)